# yade-users team mailing list archive

## Re: [Question #699807]: Particle Size distribution for fine-grained soil

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```Question #699807 on Yade changed:

Status: Open => Answered

Karol Brzezinski proposed the following answer:
Hi Hossein,

here is the problem. You want to have in your simulation particles that
differ in size by three orders of magnitude. From your PSD one can find
out that 3,4% of the mass are particles with a diameter of 1.2 microns
(0.0000012 m). On the other side, you have 12% of particles with a
diameter of 2 mm (0.002 m). Quick math can lead to the conclusion that
for one big particle you need around 10^9 of the smallest particles.
This explains why increasing the number of particles improves PSD a
little bit.

You should consider upscaling particles. It would be nice to be able to
simulate cohesive soil with a real PSD, but consider the cost. Try to
simulate a smaller volume of the soil (let's say 3% of current volume),
only with the smallest particles. Probably, you will find out that the
simulation runs extremely slow.

Also, please don't set "mass = false". In such a case the algorithm only
counts the number of the particles, not the mass.

Cheers,
Karol

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